Luminescent concrete product

ABSTRACT

Luminescent concrete compositions containing cement, fine aggregates such as sand, and a phosphor such as strontium aluminate. Glow-in-the-dark concrete products made therefrom and methods of producing such concrete products are also specified. The glow-in-the-dark concrete products demonstrate good mechanical strength (e.g. compressive strength) and skid resistance. The addition of phosphorescent strontium aluminate provides luminance that persists for up to 10 hours to the concrete products.

STATEMENT OF ACKNOWLEDGEMENT

This project was prepared with financial support from the Deanship ofScientific Research (DSR) at Imam Abdulrahman Bin Faisal University,Kingdom of Saudi Arabia under the project ID 2017-006-Eng.

BACKGROUND OF THE INVENTION Technical Field

The present disclosure relates to luminescent concrete compositionsinvolving phosphorescent strontium aluminate particles, cement, and fineaggregates, glow-in-the-dark concrete products made therefrom, andmethods for producing these concrete products.

Description of the Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Researchers are continuously looking to develop new types of materialwith improved performance by using innovative methods. One such area ofinterest is luminance, Andrew et al. [Andrew, A., Taylor, W., Tao, B.and Weiss, J. (2015): “Assessing the Performance of Glow in the DarkConcrete”, Transportation Research Record: Journal of the TransportationResearch Board, 41, pp. 1-14. DOI: 10.3141/2508-04, incorporated hereinby reference in its entirety] developed a luminescent concrete sealantthat can be applied in a variety of ways by mixing glow-in-the-darkpowder in a lubricant. However, poor durability of the developed sealantlimits its viability for practical applications. As a result, thedeveloped sealant only has limited usage in esthetical applications.

Throughout the last decade, translucent concrete has been a topic ofinterest in both academic and applied engineering sectors. TranslucentConcrete was first invented in 2001 by Hungarian architect Aron Losonczi[Alejandro, F., Hanna, K. and Fastag, K. (2004): “Design and manufactureof translucent architectural pre cast panels”, Coolest Inventions Tokyo,Time Magazine, Nov. 29.; and Carl, H. (2004).: “Seeing the future ofconstruction through translucent concrete”, The Associated Press,http://www.seattlepi.com/business/181281_translucent08.html, eachincorporated herein by reference in their entirety]. Since its advent,the application of translucent concrete has been limited toarchitectural and esthetical purposes. Research effort was devoted toimprove the durability [Basma, F., Roaa, M., Doaa, F., and Mamoun, A.(2013): “Basics of light transmitting concrete.” Global Adv. Res. J.Eng., 2(3), 76-83; and He, J., Zhou, Z., and Ou, J. (2011).: “Study onsmart transparent concrete product and its performances.” 6^(th) Int.Workshop on Advanced Smart Materials and Smart Structures Technology,International Association for Experimental Structural Engineering(IAESE), and the Asian-Pacific Network of Centers for Research in SmartStructures Technology (ANCRiSST), Dalian, China, 380-388, eachincorporated herein by reference in their entirety] and to lower thecost by embedding optical fibers in concrete materials [Saleem,M.,Shami, M. & Najjar, M. (2016).: “Development of Smart Material LaneSeparator for Increased Traffic Safety”, Journal of ConstructionEngineering and Management. DOI: 10.1061/(ASCE)C0.1943-7862.0001240;Saleem, M. (2016).: “Investigating the effect of impact loadinggenerated due to moving truck wheel on smart road lane separator.”Qassim Univer. J. Eng. Comput. Sci.; Sawant, A., Jugdar, R., and Sawant,A. (2014). “Light transmitting concrete by using optical fiber” Int. J.Invent. Eng. Sci., 3(1), 23-28; and Omran, A., and Hamou, A. T. (2016).:“Performance of glass-powder concrete in field applications.” Constr.Build. Mater., 109, 84-95, each incorporated herein by reference intheir entirety]. Furthermore, researchers have also considered usingoptical fibers as sensors by embedding them in a concrete structure toevaluate load bearing performance and detect cracks in the structure[Kalymnios, D. (2005): “Plastic optical fibers (POF) in sensing—Currentstatus and prospects.” 17^(th) Int. Conf, on Optical Fiber Sensors,International Society of Optics and Photonics (SPIE), Bruges,Belgium,97-104; Kim, K., Kollar, S., and Springer, S. G. (2011).: “Amodel of embedded fiberoptic Fabry-Perot temperature and strainsensors.” J. Comput. Mater., 27(17), 1618-1662; Shakir, A., Hassan, H.,and Safaa, A. (2014).: “Effect of plastic optical fiber on someproperties of translucent concrete.” Eng. Tech. J., 32(12), 2846-2861;and Craig, C. F. (2001): “How Fiber Optics Work”, PhD extracts,http://communication.howstuffworks.com/fiber-optic-communications/fiber-optic7.html,each incorporated herein by reference in their entirety]. However, theseapproaches are not only costly compared to non-destructive testing, butalso require skilled labor for construction and maintenance [Saleem, M.,Al-Kutti, W., Al-Akhras, N. and Haider, H. (2016). “Non-DestructiveTesting Method to Evaluate the Load Carrying Capacity of ConcreteAnchors”, Journal of Construction Engineering and Management, 142(5),17-29. DOI: 10.1061/(ASCE)CO.1943-7862.0001105, incorporated herein byreference in its entirety]. FIG. 1 presents a glow-in-the-dark bicycleway unveiled in the Netherlands. The material used on the bicycle wayrequired electrical excitation to generate luminescence. It wasdemonstrated that the material glowed for up to 8 hours, however, theglow-ability was reduced when wet. In addition, the durability of thematerial was not suited for extreme high temperature (McGrath, T.(2014). “The Netherlands debuts a futuristic highway that glows in thedark.”〈https://www.pri.org/stories/2014-04-15/netherlands-debuts-futuristic-highway-glows-dark〉(May 20, 2018); and BBC. (2014): “Glow in the dark road unveiled in theNetherlands”, (http://www.bbc.com/news/technology-27021291) (May 21,2018), each incorporated herein by reference in their entirety].

Before implementing new construction materials it is necessary tothoroughly assess the environmental impacts and long-term effects ofsuch materials on the well-being of humans and environment. Potentialrisks such as direct human exposure and leaching, which can lead tocontamination of subsoil resources [Blaisi, N. I., Cheng, W., Roessler,J., Townsend, T., Al-Abid, S. (2015). “Evaluation of the Impact of LimeSoftening Waste Disposal in Natural Environments.” Journal of WasteManagement, 43, pp. 524-532, ISSN0956-053X.doi:10.1016/j.wasman.2015.06.015, incorporated herein byreference in its entirety] should be investigated to evaluate thesuitability of new materials. In this regards, main questions that areneeded to be investigated on GiD based materials used on infrastructureprojects include: (1) is the glow-in-the-dark material made fromenvironmentally friendly substances; (2) does the glow-in-the-darkpavement leach any pollutant into the groundwater at levels greater thanthose outlined in soil and groundwater cleanup target levels by US EPA;and (3) if leaching of trace amounts of pollutants does occur, what aresome of the best practices to dispose of the pavement when it reachesthe end of life cycle.

It is evident that the application of GiD material is hampered withdurability issues and lack of sufficient knowledge related to theirenvironmental impact. In view of the foregoing, one objective of thepresent disclosure is to provide luminescent concrete compositions whichutilize phosphorescent strontium aluminate particles, cement, and fineaggregates (e.g. sand). A further objective of the present disclosure isto provide glow-in-the-dark concrete products based on said luminescentconcrete compositions and to provide methods for manufacturing saidglow-in-the-dark concrete products.

The present disclosure details the development of durableglow-in-the-dark (GiD) amended concrete that can be used for variousinfrastructure purposes. New types of GiD interlock blocks have beendeveloped by replacing the top layer with a GiD based mortar. Thisallows the interlocking blocks to absorb energy during the day time andrelease the stored energy in the form of visible light during the nighttime. Furthermore, the present disclosure also addresses the impact ofthe GiD materials on the environment and human health. Detailedenvironmental testing was conducted on GiD powder and GiD amendedconcrete to judge their suitability for use on infrastructures.

BRIEF SUMMARY OF THE INVENTION

According to a first aspect, the present disclosure relates to aluminescent concrete composition comprising a hydraulic cement, a fineaggregate comprising sand, and phosphorescent strontium aluminateparticles, wherein a weight ratio of the strontium aluminate particlesto the fine aggregate is in the range of 1:2 to 1:20, and theluminescent concrete composition is devoid of a superplasticizer.

In one embodiment, the phosphorescent strontium aluminate particlescomprise a rare earth element doped strontium aluminate.

In one embodiment, the rare earth element is at least one selected fromthe group consisting of cerium, dysprosium, europium, and neodymium.

In one embodiment, the rare earth element doped strontium aluminatefurther comprises a promoter selected from the group consisting ofboron, lithium, sodium, potassium, magnesium, calcium, barium, chromium,and manganese.

In one embodiment, the phosphorescent strontium aluminate particles havean average particle size of 1-15 µm.

In one embodiment, the sand has a bulk specific gravity of 2.2-2.8, anda water absorption of 0.2%-1.0%.

In one embodiment, the luminescent concrete composition has a weightpercentage of the fine aggregate ranging from 35-60 wt% relative to atotal weight of the luminescent concrete composition.

In one embodiment, the hydraulic cement is an ordinary Portland cement.

In one embodiment, the luminescent concrete composition has a weightpercentage of the hydraulic cement ranging from 30-60 wt% relative to atotal weight of the luminescent concrete composition.

In one embodiment, the luminescent concrete composition consistsessentially of the hydraulic cement, the fine aggregate comprising sand,and the phosphorescent strontium aluminate particles, wherein a weightratio of the strontium aluminate particles to the fine aggregate is inthe range of 1:2 to 1:20.

According to a second aspect, the present disclosure relates to aluminescent concrete slurry comprising the luminescent concretecomposition of the first aspect, and 10-25 wt% water relative to a totalweight of the luminescent concrete slurry.

According to a third aspect, the present disclosure relates to aglow-in-the-dark concrete block including a surface layer containing acured form of the luminescent concrete slurry of the second aspect, anda base concrete block, wherein at least a portion of a surface of thebase concrete block is coated by the surface layer.

In one embodiment, the surface layer has a thickness of 1-20 mm, and athickness ratio of the surface layer to the base concrete block is inthe range of 0.02:1 to 0.2:1.

In one embodiment, the base concrete block comprises a cured form of aconcrete slurry comprising cement, a fine aggregate comprising sand, acoarse aggregate comprising limestone, and water, and which is devoid ofphosphorescent strontium aluminate particles.

In one embodiment, the limestone has an average particle size of 2-15mm, a bulk specific gravity of 2.0-3.0, and a water absorption of1.0%-3.0%.

In one embodiment, the glow-in-the-dark concrete block has an intensityof glow of 2-15 candelas per square meter for a period of 0.1-10 hoursupon excitation with sun light at an intensity of 50-300 watts for 2-20minutes.

In one embodiment, the glow-in-the-dark concrete block has a compressivestrength of 43-50 MPa according to ASTM C936/C936M.

In one embodiment, the surface layer has a skid resistance value of100-150.

In one embodiment, a volume of the base concrete block is greater thanthat of the surface layer.

According to a fourth aspect, the present disclosure relates to aluminescent concrete material comprising a cured form of the luminescentconcrete slurry of the second aspect.

The foregoing paragraphs have been provided by way of generalintroduction, and are not intended to limit the scope of the followingclaims. The described embodiments, together with further advantages,will be best understood by reference to the following detaileddescription taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is a picture showing a glow-in-the-dark (GiD) bicycle way in theNetherlands.

FIG. 2A is a picture showing phosphorescent strontium aluminateparticles before photo-activation.

FIG. 2B is a picture showing phosphorescent strontium aluminateparticles after photo-activation.

FIG. 3A is a picture showing the hydraulic press used for preparing GiDconcrete blocks.

FIG. 3B is a picture showing GiD concrete blocks.

FIG. 3C is a picture showing a close-up view of a GiD concrete block.

FIG. 4A is a picture showing GiD concrete blocks seen in daylight.

FIG. 4B is a picture showing the GiD concrete blocks of FIG. 4A seen atnight.

FIG. 5A is a picture showing a cracking pattern of a GiD concrete blocksample 1.

FIG. 5B is a picture showing a cracking pattern of a GiD concrete blocksample 2.

FIG. 5C is a picture showing a cracking pattern of a GiD concrete blocksample 3.

FIG. 6 is a particle size distribution curve of phosphorescent strontiumaluminate particles.

FIG. 7 shows the effect of excitation duration on the glow intensity ofGiD concrete blocks having weight ratios of the strontium aluminateparticles to the fine aggregate of 10:90, 15:85, and 20:80,respectively.

FIG. 8 is a material feasibility triangle diagram.

FIG. 9 is a bar graph comparing concentrations of major contaminantsincluding Al and Fe elements in the GiD concrete block to those at soilcleanup target level (SCTL).

FIG. 10 is a bar graph comparing concentrations of major contaminantsincluding Cu, Li, and Pb elements in the GiD concrete block to those atsoil cleanup target level (SCTL).

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present disclosure will now be described more fullyhereinafter with reference to the accompanying drawings, in which some,but not all embodiments of the disclosure are shown.

As used herein, the words “a” and “an” and the like carry the meaning of“one or more.” Within the description of this disclosure, where anumerical limit or range is stated, the endpoints are included unlessstated otherwise. Also, all values and subranges within a numericallimit or range are specifically included as if explicitly written out.

According to a first aspect, the present disclosure relates to aluminescent concrete composition comprising a hydraulic cement, a fineaggregate comprising sand, and phosphorescent strontium aluminateparticles. The luminescent concrete composition disclosed herein refersto a dry, un-hydrated composition, and all recited weight ratios relatedto the concrete composition are based on the dry composition. Aluminescent concrete slurry, which is wet and hardens over time, may beformed once water is added to the luminescent concrete composition.

As used herein, the terms “luminescent” or “luminescence” describe amaterial that emits light upon excitation from a non-thermal source suchas chemical reactions, electrical energy, electromagnetic rays, andmechanical stress, etc. There are different types of luminescencecategorized by excitation source, e.g. bioluminescence originated frombiochemical reactions in a living organism, mechanoluminescencegenerated by mechanical stress, and photoluminescence resulted fromabsorption of photons. Similar to fluorescence, phosphorescence is aform of photoluminescence involving relative slow emission of light by asubstance that has absorbed light or other electromagnetic radiation.However, unlike fluorescence, where the substance would cease to glowalmost immediately upon removal of the excitation source, phosphorescentmaterials would continue to glow and emit light for some time after theradiation source has been turned off. Hence, it is a persistentphenomenon compared to fluorescence. Phosphorescence is often themechanism used for “glow-in-the-dark” (GiD) materials, which are chargedby exposure to light. Unlike the relatively swift reactions influorescence such as those seen in a common fluorescent tube, GiDmaterials store the absorbed energy for a longer time at a metastablestate. A phosphorescence lifetime is the average time needed for thestored energy to get released in a phosphorescent material.

In one or more embodiments, the luminescent concrete composition of thepresent disclosure comprises phosphorescent strontium aluminateparticles. Strontium aluminate having a formula of SrAl₂O₄ is anonflammable, pale yellow, monoclinic crystalline powder. Strontiumaluminate may be present in other formulae such as SrAl₄O₇ with amonoclinic crystalline structure, Sr₃Al₂O₆ with a cubic crystallinestructure, SrAl₁₂O₁₉ with a hexagonal crystalline structure, andSr₄Al₁₄O₂₅ with an orthorhombic crystalline structure. In one or moreembodiments, the phosphorescent strontium aluminate particles usedherein comprise strontium aluminate with a formula of SrAl₂O₄. It isequally envisaged that strontium aluminate with other formulaeincluding, but not limited to, SrAl₄O₇, Sr₃Al₂O₆, SrAl₁₂O₁₉, andSr₄Al₁₄O₂₅ may be used in addition to, or in lieu of SrAl₂O₄.

When doped with small amounts of a suitable dopant such as rare earthand/or transition metal elements, strontium aluminate may act as anefficient photoluminescent phosphor. In one or more embodiments, thephosphorescent strontium aluminate particles of the present disclosurecomprise a rare earth element doped strontium aluminate. In a preferredembodiment, the rare earth element is at least one selected from thegroup consisting of cerium, dysprosium, europium, and neodymium.Exemplary rare earth element doped strontium aluminates include, but arenot limited to, cerium doped strontium aluminate, europium dopedstrontium aluminate, europium and neodymium doped strontium aluminate,and europium and dysprosium doped strontium aluminate (e.g.Sr_(0.95)Eu_(0.02)Dy_(0.03)Al₂O₄, andSr_(3.84)Eu_(0.06)Dy_(0.10)Al₁₄O₂₅). In one embodiment, the rare earthelement may be present at a molar amount of 2-15 mol%, preferably 3-10mol%, more preferably 4-8 mol% relative to the amount of strontiumaluminate. However, in certain embodiments, the molar amount of the rareearth element may be less than 2 mol% or greater than 15 mol% relativeto the amount of strontium aluminate.

In one or more embodiments, the rare earth element doped strontiumaluminate further comprises one or more promoters selected from thegroup consisting of boron, lithium, sodium, potassium, magnesium,calcium, barium, chromium, and manganese. Exemplary rare earth elementdoped strontium aluminates further comprising a promoter include, butare not limited to, cerium doped strontium aluminate promoted bymagnesium, cerium doped strontium aluminate promoted by manganese, andeuropium and dysprosium doped strontium aluminate promoted by boron,lithium, sodium, potassium, magnesium, calcium, barium, or chromium. Inone embodiment, the promoter may be present at a molar amount of 0.005-5mol%, preferably 0.05-1 mol%, more preferably 0.1-0.5 mol% relative tothe amount of strontium aluminate. However, in certain embodiments, themolar amount of the promoter may be less than 0.005 mol% or greater than5 mol% relative to the amount of strontium aluminate. When present, thepromoter may be doped on strontium aluminate.

As used herein, “doped” refers to the rare earth element and/or thepromoter being affixed on an outer surface of strontium aluminate orwithin pore spaces of strontium aluminate. The rare earth element and/orthe promoter may be affixed via strong atomic bonds (e.g. metallic,ionic, and covalent bonds) and/or weak interactions such as van derWaals, or hydrogen bonds. For example, the phosphorescent strontiumaluminate particles may comprise the rare earth element (e.g. europiumand dysprosium) embedded in and become integral with the crystallinelattice structure of the strontium aluminate.

As defined herein, an average particle size refers to the longest lineardimension of a particle. In one or more embodiments, the phosphorescentstrontium aluminate particles have an average particle size of 0.5-15µm, preferably 1-12 µm, preferably 2-10 µm, preferably 3-8 µm,preferably 4-7 µm, preferably 5-6 µm.As used herein, the coefficient ofvariation or relative standard deviation is expressed as a percentageand defined as the ratio of the particle size standard deviation (σ) tothe particle size mean (µ) multiplied by 100. In a preferred embodiment,the phosphorescent strontium aluminate particles have a coefficient ofvariation of less than 50%, preferably less than 40%, preferably lessthan 30%, preferably less than 20%, preferably less than 15%, preferablyless than 10%. In a preferred embodiment, the phosphorescent strontiumaluminate particles have a particle size distribution ranging from 10%of the average particle size to 200% of the average particle size,preferably 50-150%, preferably 75-125%, preferably 80-120%, preferably90-110%.

Photophysical properties of a strontium aluminate phosphor includingabsorption-emission profile, phosphorescence lifetime, and quantum yieldmay be dependent on various factors including molecular formula ofstrontium aluminate, chemical identities of the dopant and the promoter,internal crystal structure (e.g. crystal packing) of the strontiumaluminate phosphor, and particle size of the phosphor. In oneembodiment, the phosphorescent strontium aluminate particles have aphosphorescence emission peak of 400-700 nm, preferably 425-675 nm,preferably 450-650 nm, preferably 475-625 nm, preferably 500-600 nm,preferably 525-575 nm at an excitation wavelength of 200-425 nm,preferably 225-400 nm, preferably 250-375 nm, preferably 275-350 nm,preferably 300-325 nm. In one embodiment, the phosphorescent strontiumaluminate particles used herein have a phosphorescence lifetime rangingfrom 0.1-40 hours, preferably 1-20 hours, preferably 2-15 hours,preferably 3-10 hours, preferably 4-8 hours. In certain embodiments, thephosphorescent strontium aluminate particles have a phosphorescencelifetime less than 0.1 hour or greater than 40 hours.

As used herein, quantum yield (Φ) refers to the phosphorescence quantumyield and gives the efficiency of the phosphorescence process. It isdefined as the ratio of the number of photons emitted relative to thenumber of photons absorbed. In one embodiment, the phosphorescentstrontium aluminate particles used herein have a quantum yield in arange of 0.02-0.9, preferably 0.05-0.8, preferably 0.1-0.7, preferably0.2-0.6, preferably 0.3-0.5 for phosphorescence emission peak of 400-700nm, preferably 425-675 nm, preferably 450-650 nm, preferably 475-625 nm,preferably 500-600 nm, preferably 525-575 nm at an excitation wavelengthof 200-425 nm, preferably 225-400 nm, preferably 250-375 nm, preferably275-350 nm, preferably 300-325 nm.

The phosphorescent strontium aluminate particles disclosed hereindemonstrate good compatibility with other ingredients of the luminescentconcrete composition such as hydraulic cements and fine aggregatesdiscussed hereinafter. In one embodiment, the difference ofaforementioned phosphorescence emission peaks between the phosphorescentstrontium aluminate particles present in the luminescent concretecomposition and the phosphorescent strontium aluminate particles aloneis less than 35%, preferably less than 25%, more preferably less than15%, such as for example 5-30%, 10-20%, or 12-14%. In anotherembodiment, the difference of phosphorescence quantum yields between thephosphorescent strontium aluminate particles present in the luminescentconcrete composition and the phosphorescent strontium aluminateparticles alone is less than 25%, preferably less than 20%, morepreferably less than 10%, such as for example, 2-20%, 5-15%, or 8-12%.

The phosphorescent strontium aluminate particles used herein may beprepared by techniques generally known to those skilled in the artincluding, but not limited to, sol-gel process, chemical precipitation,hydrothermal co-precipitation, solid-state reaction, and combustionsynthesis technique. Alternatively, the phosphorescent strontiumaluminate particles used herein may be available from commercial vendorsincluding, without limitation, Sigma Aldrich, Alfa Aesar, United Mineraland Chemical Corp., and Techno Glow Products.

In one embodiment, the luminescent concrete composition has a weightpercentage of the phosphorescent strontium aluminate particles rangingfrom 1-30% relative to a total weight of the luminescent concretecomposition, preferably 3-28%, preferably 5-25%, preferably 8-20%,preferably 10-18%, preferably 12-15% relative to the total weight of theluminescent concrete composition.

As defined herein, the term “bulk specific gravity” refers to a ratio ofthe weight of a bulk volume of a substance to the weight of an equalvolume of a reference substance, e.g. water. As used herein, waterabsorption refers to the penetration of water into aggregate particleswith resulting increase in particle weight.

In one or more embodiments, the luminescent concrete composition of thepresent disclosure comprises a fine aggregate. In one embodiment, thefine aggregate used herein has an average particle size in a range of0.05-1 mm, preferably 0.1-0.8 mm, preferably 0.2-0.6 mm, preferably0.3-0.5 mm. In a preferred embodiment, the fine aggregate used hereinhas a bulk specific gravity of 2.0-3.0, preferably 2.2-2.9, preferably2.3-2.8, preferably 2.4-2.7, or about 2.66. In a preferred embodiment,the luminescent concrete composition of the present disclosure comprisesa fine aggregate having a water absorption of 0.2-1.0%, preferably0.3-0.8%, preferably 0.4-0.7%, or about 0.6%.

In one or more embodiments, the luminescent concrete composition has aweight percentage of the fine aggregate ranging from 35-60% relative toa total weight of the luminescent concrete composition, preferably38-58%, preferably 40-55%, preferably 42-52%, preferably 45-50%,preferably 46-48% relative to the total weight of the luminescentconcrete composition. In a preferred embodiment, a weight ratio of thestrontium aluminate particles to the fine aggregate is in the range of1:2 to 1:20, preferably 1:3 to 1:16, preferably 1:4 to 1:12, preferably1:5 to 1:10, preferably 1:6 to 1:9, preferably 1:7 to 1:8.

In a preferred embodiment, the fine aggregate is sand, more preferablydesert sand. As used herein, “sand” refers to a naturally occurringgranular material composed of finely divided rock and mineral particles.It is defined by size in being finer than gravel and coarser than silt.The composition of sand varies, depending on the local rock sources andconditions, but the most common constituent of sand is silica (silicondioxide, or SiO₂), usually in the form of quartz. In terms of particlesize, sand particles range in diameter from 0.0625 mm to 2 mm. Anindividual particle in this range is termed a sand grain. By definitionsand grains are between gravel (particles ranging from 2 mm to 64 mm)and silt (particles ranging from 0.004 mm to 0.0625 mm).

In a preferred embodiment, the fine aggregate of the luminescentconcrete composition is desert sand with an average particle size ofless than 800 µm, preferably less than 600 µm, preferably less than 500µm, preferably less than 400 µm, preferably less than 300 µm, preferablyless than 200 µm, preferably less than 100 µm, such as for example500-700 µm, preferably 525-675 µm, preferably 550-650 µm.As used herein,the coefficient of variation or relative standard deviation is expressedas a percentage and defined as the ratio of the particle size standarddeviation (σ) to the particle size mean (µ) multiplied by 100. In apreferred embodiment, the fine aggregate of the concrete composition isdune sand having a coefficient of variation of less than 35%, preferablyless than 30%, preferably less than 25%, preferably less than 20%,preferably less than 15%, preferably less than 10%. In a preferredembodiment, the fine aggregate of the luminescent concrete compositionis desert sand having a particle size distribution ranging from 10% ofthe average particle size to 200% of the average particle size,preferably 50-150%, preferably 75-125%, preferably 80-120%, preferably90-110%. Even though the phosphorescent strontium aluminate particlesmay have a particle size similar to the fine aggregate used herein, itis considered that the phosphorescent strontium aluminate particles area separate and distinct component from the fine aggregate in thecurrently disclosed luminescent concrete composition.

As used herein, the term “cement” refers to a composition or substancewith one or more constituents that are capable of binding othermaterials together once cured. Generally, cement may include a number ofdry constituents chosen based on the desired ratio or class of cement tobe produced. Thus, cement refers to a dry composition before curingunless the context clearly dictates otherwise, for example, in a wetconcrete slurry, or in a cured cement material. In one embodiment, thecement used herein may include hydraulic cement, non-hydraulic cement,or a combination thereof. In a preferred embodiment, the cementcomprises Portland cement, a basic ingredient of concrete, mortar,stucco, and/or non-specialty grout, which is present as a fine powder,and produced by heating limestone and clay materials in a kiln to formclinker, grinding the clinker, and adding small amounts of othermaterials. Several types of Portland cement are available with the mostcommon being called ordinary Portland cement (OPC) which is grey incolor. Exemplary Portland cement includes, without limitation, ordinaryPortland cement (OPC) Type I, Type II, Type III, Type IV, Type V, and acombination thereof (in accordance with either ASTM C 150 or EuropeanEN-197 standard). Portland cement type IA, type IIA, and/or type IIIAmay also be used, which have the same composition as type I, II, and IIIexcept that an air-entraining agent is ground into the mix (also inaccord with the ASTM C 150 standard).

In one embodiment, the cement comprises a cement blend of two or moretypes of cement, for example, a blend comprising Portland cement andnon-Portland hydraulic cement. In a further embodiment, the cement is inthe dry form. If needed to set, water is typically added after thecement is mixed with the other components or ingredients, for example,the phosphorescent strontium aluminate particles, fine aggregates (e.g.sand), and/or coarse aggregates, and it is then ready to be hardened orset.

As used herein, the term “hydraulic cement” refers to any inorganiccement that hardens, cures or sets due to hydration. Exemplary hydrauliccements include Portland cements, aluminous cements, fly ash cements,and the like. Hydraulic cements set and develop compressive strength dueto the occurrence of a hydration reaction which allows them to set orcure under the presence of water. The physical properties of the setcement relate to the crystalline structure of thecalcium-silicate-hydrates formed during hydration reaction. For example,conventional Portland cements form an interlocking crystalline networkof, e.g. tricalcium silicate, dicalcium silicate, tetracalcium aluminumferrite and calcium hydroxide crystals. These crystals interconnect toform an interlocking crystalline structure which provides physicalstrength and a degree of resiliency. Hydration products of Portlandcements may also form crystalline or amorphous interlocking networks ofthe hydration products such as calcium silicate hydrate, calciumhydroxide (Portlandite), calcium silicate (Larnite), aluminum calciumiron oxide (e.g. Ca₂FeAlO₅), and/or silica.

In one or more embodiments, the hydraulic cement is present in theluminescent concrete composition at an amount of 25-65 wt%, preferably30-60 wt%, more preferably 40-50 wt% relative to a total weight of theluminescent concrete composition. However, in some embodiments, thehydraulic cement is present in an amount of less than 25 wt% or greaterthan 65 wt% relative to a total weight of the luminescent concretecomposition. In a preferred embodiment, the hydraulic cement is anordinary Portland cement. In one embodiment, the hydraulic cement usedherein has a specific gravity of 2-3.8, preferably 2.5-3.4, morepreferably 2.9-3.2, or about 3.15.

It is equally envisaged that the present disclosure may be adapted toincorporate white Portland cement. White Portland cement or whiteordinary Portland cement (WOPC) is similar to ordinary grey Portlandcement in all respects except for its high degree of whiteness. The mainrequirement is to have low iron content which should be less than 0.5wt% relative to the total weight of the cement expressed as Fe₂O₃ forwhite cement and less than 0.9 wt% for off-white cement. In certainembodiments, the iron oxide as ferrous oxide (FeO) obtained via slightreducing conditions (zero excess oxygen in the kiln) may give the cementa green tinge. Other metals including, but not limited to, Cr, Mn, Ti,etc. can also in trace content give color tinges to the cement of thepresent disclosure. In a related embodiment, the luminescent concretecomposition may further comprise a pigment intended to modify the colorof the composition and concrete made therefrom for aesthetic appeal.

As used herein, a “plasticizer” is an additive that increases theplasticity or fluidity of slurry. Plasticizers increase the workabilityof “fresh” concrete, allowing it to be placed more easily, with lessconsolidating effort. A superplasticizer is a plasticizer with fewerdeleterious effects. A “superplasticizer” refers a chemical admixtureused herein to provide a well-dispersed particle suspension in the wetconcrete slurry. The superplasticizer may be used to prevent particlesegregation and to improve the flow characteristics of the wet concreteslurry. For instance, Polycarboxylate ether-based superplasticizers arecomposed of a methoxy-polyethylene glycol copolymer (side chain) graftedwith methacrylic acid copolymer (main chain). Polycarboxylateether-based superplasticizers may allow a significant water reduction ata relatively low dosage, thereby providing good particle dispersion inthe wet concrete slurry. Exemplary superplasticizers include, but arenot limited to, a polycarboxylate, e.g. a polycarboxylate derivativewith polyethylene oxide side chains, a polycarboxylate ether (PCE)superplasticizer, such as the commercially available Glenium 51®, alkylcitrates, sulfonated naphthalene, sulfonated alene, sulfonated melamine,lignosulfonates, calcium lignosulfonate, naphthalene lignosulfonate,polynaphthalenesulfonates, formaldehyde, sulfonated naphthaleneformaldehyde condensate, acetone formaldehyde condensate,polymelaminesulfonates, sulfonated melamine formaldehyde condensate,polycarbonate, other polycarboxylates, other polycarboxylate derivativescomprising polyethylene oxide side chains, and the like and mixturesthereof.

In some embodiments, the luminescent concrete composition describedherein comprise substantially no superplasticizer, for instance, lessthan 0.05 wt% of superplasticizer, preferably less than 0.01 wt%, morepreferably less than 0.001 wt% of superplasticizer, relative to a totalweight of the luminescent concrete composition. In at least oneembodiment, the luminescent concrete composition described herein isdevoid of a superplasticizer. Non-limiting examples of superplasticizerthat may be excluded from the luminescent concrete composition disclosedherein include sulfonated melamine, and polyethylene condensates. Theexclusion of superplasticizer may lower the cost while having nodeleterious effect on the physical strength of the concrete blocksresulting from the luminescent concrete composition.

In one embodiment, one or more components selected from the groupconsisting of limestone, metakaolins, artificial pozzolans, modifiedpolyvinyl resins, and dispersant of vinyl acetate and ethylenecopolymers are excluded from the luminescent concrete compositiondescribed herein. In another embodiment, additives including acrylicemulsions, polyethylene emulsion wax, paraffin wax, and silicone waterrepellents are excluded from the luminescent concrete compositiondescribed herein.

In one or more embodiments, the luminescent concrete composition of thepresent disclosure consists essentially of the hydraulic cement, thefine aggregate comprising sand, and the phosphorescent strontiumaluminate particles. In a related embodiment, a weight ratio of thestrontium aluminate particles to the fine aggregate (e.g. sand) is inthe range of 1:2 to 1:20, preferably 1:3 to 1:16, preferably 1:4 to1:12, preferably 1:5 to 1:10, preferably 1:6 to 1:9, preferably 1:7 to1:8.

According to another aspect, the present disclosure relates to aluminescent concrete slurry comprising the luminescent concretecomposition disclosed herein in any of its embodiments, and water. Thewater may be potable water, tap water, freshwater or seawater, and maybe taken from a natural source, such as an aquifer, lake, or ocean, andmay be filtered to remove large solids before using. In one or moreembodiments, the water may be present in the luminescent concrete slurryin an amount of 10-25 wt% by weight of the luminescent concrete slurry,preferably 12-20 wt%, more preferably 15-18 wt% by weight of theluminescent concrete slurry. In a related embodiment, a weight ratio ofthe water to the hydraulic cement is in the range of 1:1 to 1:10,preferably 2:3 to 1:5, more preferably 1:2 to 1:3, or about 2:5. Ingeneral, the amount of water used in the concrete slurry depends uponthe type of hydraulic cement selected and the job conditions at hand.Thus, in other embodiments, the water may be present in the luminescentconcrete slurry in an amount of less than 10 wt% or greater than 25 wt%by weight of the wet concrete slurry. The amount of water used may varyover a wide range, depending upon factors such as the chemical identityof the cement and the required consistency of the luminescent concreteslurry.

According to another aspect, the present disclosure relates to aglow-in-the-dark concrete block including a surface layer containing acured form of the luminescent concrete slurry disclosed herein in any ofits embodiments, and a base concrete block. Preferably, at least aportion of a surface of the base concrete block is coated by the surfacelayer.

In one embodiment, the base concrete block comprises a cured form of aconcrete slurry comprising cement, a fine aggregate comprising sand, acoarse aggregate comprising limestone, and water, and which is devoid ofphosphorescent strontium aluminate particles.

In one or more embodiments, the concrete slurry used herein forpreparing the base concrete block comprises the fine aggregate havingsimilar properties (e.g. particle size, bulk specific gravity, waterabsorption) as described previously. The concrete slurry may have aweight percentage of the fine aggregate ranging from 20-40 wt% relativeto a total weight of the concrete slurry, preferably 25-35 wt%, morepreferably 28-32 wt% relative to the total weight of the concreteslurry. Preferably, the fine aggregate present in the concrete slurry issand, more preferably desert sand. In one or more embodiments, theconcrete slurry comprises a cement sharing similar properties (e.g.cement type, chemical composition) with the one used in the luminescentconcrete composition of the first aspect. The concrete slurry may have aweight percentage of the cement ranging from 25-45 wt% relative to atotal weight of the concrete slurry, preferably 28-40 wt%, morepreferably 30-35 wt% relative to the total weight of the concreteslurry. Preferably, the cement is an ordinary Portland cement.Furthermore, the concrete slurry may have a weight percentage of waterranging from 8-25 wt% relative to a total weight of the concrete slurry,preferably 10-20 wt%, more preferably 12-15 wt% relative to the totalweight of the concrete slurry.

In one or more embodiments, the concrete slurry for the base concreteblock comprises a coarse aggregate. In one embodiment, the coarseaggregate has an average particle size in a range of 2-15 mm, preferably3-10 mm, preferably 4-9 mm, preferably 5-8 mm. In a preferredembodiment, the coarse aggregate used herein has a specific gravity of2.0-3.0, preferably 2.1-2.8, preferably 2.2-2.6, preferably 2.3-2.5, orabout 2.4. In a preferred embodiment, the concrete slurry comprises acoarse aggregate having a water absorption of 0.5-4.0%, preferably1.0-3.0%, preferably 1.5-2.5%, or about 2.0%. In a preferred embodiment,the concrete slurry has a weight percentage of the coarse aggregateranging from 28-45% relative to the total weight of the composition,preferably 30-42%, preferably 32-40%, preferably 35-38% relative to thetotal weight of the concrete slurry.

As used herein, limestone refers to a sedimentary rock composed largelyof the minerals calcite and aragonite, which are different crystal formsof calcium carbonate (CaCO₃). Limestone is naturally occurring and canbe found in skeletal fragments of marine organisms such as coral,forams, and molluscs. In one or more embodiment, the concrete slurry forthe base concrete block comprises limestone as the coarse aggregate.

In one or more embodiments, the concrete slurry for the base concreteblock comprises substantially no phosphorescent strontium aluminateparticles, for instance, less than 0.1 wt% of phosphorescent strontiumaluminate particles, preferably less than 0.05 wt%, more preferably lessthan 0.01 wt% of phosphorescent strontium aluminate particles, relativeto a total weight of the concrete slurry. In at least one embodiment,the concrete slurry described herein is devoid of phosphorescentstrontium aluminate particles.

Concrete production is the process of mixing together the variousingredients (water, aggregate, cement, additives, etc.) to produceconcrete. Concrete production is time sensitive. Thorough mixing isadvantageous for the production of uniform high quality concrete. Eachsection of the glow-in-the-dark concrete block described herein (e.g.the base concrete block, the surface layer) may be prepared bysequentially pouring different components into a concrete mixer (e.g. apaddle mixer, a drum mixer, a rotating mixer). For example, theaforementioned luminescent concrete composition including thephosphorescent strontium aluminate particles, the fine aggregate, andthe cement, and the base concrete including the fine and coarseaggregates and the cement are each dry-mixed in concrete mixers for atime period ranging from 30 seconds-30 minutes, 60 seconds-20 minutes,or 5-10 minutes. Preferably, mixing the aggregates, the cement, andother necessary components (e.g. phosphorescent strontium aluminateparticles) forms a homogeneous dry mixture. Following the dry mixingprocess, water is added to the dry mixture to form a wet concreteslurry. The water is slowly poured into the concrete mixer while theconcrete mixer turns the dry mixture for a time period ranging from 1-10minutes, 2-8 minutes, or 3-6 minutes thereby forming a concrete slurry(e.g. the luminescent concrete slurry, the concrete slurry for the baseconcrete block). Preferably, the water is mixed into the dry mixture fora time period of about 1-10 minutes, 2-8 minutes, or 3-6 minutes.

As used herein, casting refers to the process in which a fluid material(i.e. the wet concrete slurry) is poured into a mold, which contains ahollow cavity of a desired shape, and then allowed to solidify. Thesolidified part is also known as a casting, which is ejected, demoldedor broken out of the mold to complete the process. Concrete is preparedas a viscous fluid so that it may be poured into forms to give theconcrete its desired shape.

The concrete slurry may be compacted in the mold by using a hydraulicpress, a vibrating table, a steel rod or a trowel. Preferably, ahydraulic press is used for compacting. In one embodiment, the concreteslurry may be poured into the bottom of a mold thereby forming a castedwet base concrete. The luminescent concrete slurry may be placed on topof the casted wet base concrete to form a casted luminescent surfacelayer. Alternatively, the luminescent concrete slurry may be poured intothe bottom of the mold to form a casted luminescent surface layer. Theconcrete slurry may be placed on top of the casted luminescent surfacelayer thereby forming a casted wet base concrete. Preferably, a singlecasted article is formed when the casted luminescent surface layer andthe casted wet base concrete merge at the boundary between the two. Thesingle casted article thus contains two distinct and contiguous layersincluding the casted luminescent surface layer and the casted wet baseconcrete. The aforementioned casting may be performed at a temperatureof 10-40° C., preferably 15-35° C., more preferably 23-27° C. In oneembodiment, the single casted article may be cured for a time period of2-48 hours, 6-36 hours, or 12-24 hours and then removed from the mold,which results in a glow-in-the-dark concrete block. Preferably, thejunction between cured forms of the casted luminescent surface layer andthe casted wet base concrete is substantially undetectable as the twoare cured concurrently.

In one embodiment, the glow-in-the-dark concrete block comprisespartially stratified layers whereby the casted luminescent surface layerdoes not form a distinct boundary with the casted base layer. Forexample, the casted luminescent surface layer may diffuse or partiallydiffuse into the casted base layer, and the boundary between the twobecomes a heterogeneous phase comprising components from both layers.The diffusion phenomenon may occur when layering the luminescent surfacelayer on top of the base layer during aforementioned process ofproducing and curing of the glow-in-the-dark concrete block.

The glow-in-the-dark concrete block may be left to further cure for alength of time necessary to achieve a desired mechanical property, suchas a desired compressive strength. Preferably the glow-in-the-darkconcrete block, left to cure, will harden with a mechanical strength(e.g. compressive or tensile strength) that increases over the curingtime. However, a strength will reach a maximum value within a certaintime of curing, for example, within 28 days. In one embodiment, theglow-in-the-dark concrete block may be left to further cure for a timeperiod of 1-30 days, preferably 5-28 days, more preferably 14-21 days,though in certain embodiments, the high performance concrete may beconsidered cured in less than 1 day or after 30 days. Theglow-in-the-dark concrete block may be further cured at a temperature of10-40° C., 15-35° C. or 20-28° C. Methods of preparing and curing wetconcrete slurries are generally known to those skilled in the art.During the hydration and hardening period, the glow-in-the-dark concreteblock may be kept under controlled temperature and humid atmosphere.

The cured form of the casted wet base concrete becomes the base concreteblock, while the cured form of the casted luminescent surface layerbecomes the surface layer of the glow-in-the-dark concrete block (seeFIGS. 3A, B and C). In one embodiment, the surface layer of theglow-in-the-dark concrete block has a thickness of 1-20 mm, preferably2-10 mm, more preferably 4-6 mm, or about 5 mm. In a preferredembodiment, a thickness ratio of the surface layer to the base concreteblock is in the range of 1:2 to 1:60, preferably 1:5 to 1:40, preferably1:10 to 1:30, preferably 1:12 to 1:25, preferably 1:14 to 1:20,preferably 1:15 to 1:18, or about 1:16. In one or more embodiments, avolume of the base concrete block is greater than that of the surfacelayer. Preferably, the volume of the base concrete block is greater thanthat of the surface layer by 200-2,000%, 400-1,500%, 500-1,200%, or800-1,000%.

The glow-in-the-dark concrete block of the present disclosure may be ofany shape desired including, but not limited to, a rectilinear shape, atriangular prism, a rectangular cuboid, a pentagonal prism, a hexagonalprism, an octagonal prism, a conical, a pyramid, and a cylinder. In apreferred embodiment, the glow-in-the-dark concrete block is ofrectangular cuboid shape having a length in a range of 50-800 mm,preferably 100-600 mm, preferably 125-400 mm, preferably 150-300 mm, orabout 200 mm, a width in a range of 25-400 mm, preferably 50-300 mm,preferably 60-200 mm, preferably 70-150 mm, or about 100 mm, and aheight in a range of 15-300 mm, preferably 30-250 mm, preferably 40-200mm, preferably 50-150 mm, preferably 60-100 mm, or about 80 mm. In oneor more embodiments, a portion of a surface of the base concrete blockis coated by the surface layer. In one embodiment, the surface layer,which is luminescent, may be located on 1 side of the glow-in-the-darkconcrete block, up to 2 sides, up to 4 sides, or up to 5 sides of theconcrete block. Preferably, the sides on which the surface layer islocated may be those visible and exposed to external environment (e.g.sun light).

The glow-in-the-dark concrete blocks may be produced with hollow centers(cores) to reduce weight or improve insulation. The glow-in-the-darkconcrete blocks may adopt a variety of specialized shapes to allowspecial construction features. U-shaped blocks or knockout blocks mayhave notches to allow the construction of bond beams or lintelassemblies. Blocks with a channel on the end or “jamb blocks” allowdoors to be secured to wall assemblies. Blocks with grooved ends permitthe construction of control joints allowing a filler to be anchoredbetween the block ends. Other features such as “bullnoses” may beincorporated. A wide variety of decorative profiles also exist.

Because of the presence of the phosphorescent strontium aluminateparticles, the glow-in-the-dark concrete block disclosed herein willluminesce after charging with electromagnetic radiation (e.g. sunlight). Furthermore, such luminescence will persist after the radiationsource has been removed or ceased. Importantly, the glow-in-the-darkconcrete block concrete block appears to be a standard block articlewhen viewed in daylight, while remains visible at night under poorlighting conditions (see FIGS. 4A and B). In one or more embodiments,the glow-in-the-dark concrete block disclosed herein in any of itsembodiments has an intensity of glow of 2-15 candelas per square meter(cd/m²), preferably 4-10 cd/m², more preferably 6-8 cd/m² for a periodof 0.1-20 hours, 1-15 hours, 2-10 hours, or 4-8 hours upon excitationwith sun light. The intensity of glow of a material may be examined byconventional techniques known to those skilled in the art, for example,by using a photometer to count the number of photons emitted by thematerial as a function of time.

As used herein, the sun light may be natural solar light or simulatedsolar light. Other light sources that may be used in addition to, or inlieu of the sun light include, but are not limited to, UV light, laserlight, incandescent light, and the like. Exemplary light sourcesinclude, but are not limited to, a xenon lamp such as a xenon arc lampand a xenon flash lamp, a mercurial lamp, a metal halide lamp, an LEDlamp, a solar simulator, and a halogen lamp. In certain embodiments, twoor more light sources may be used. In a preferred embodiment, naturalsunlight may be used as the light source. In another preferredembodiment, a simulated solar light may be used as the light source. Thelight source used to excite the glow-in-the-dark concrete block may havean intensity of 25-500 watts, 50-300 watts, 100-200 watts, or about 150watts at a position 5-100 cm, 10-75 cm, or 20-50 cm away from theclosest surface of the concrete block. In one or more embodiments, theduration of excitation ranges from 2-30 minutes, preferably 5-20minutes, more preferably 10-15 minutes.

As defined herein, compressive strength is the capacity of a material orstructure to withstand compressive loads, as opposed to tensilestrength, which is the capacity of a material or structure to withstandtensile loads. In one or more embodiments, the glow-in-the-dark concreteblock has a compressive strength of 40-60 MPa, preferably 43-50 MPa,more preferably 45-48 MPa. In one embodiment, the compressive strengthof the glow-in-the-dark concrete block is determined by ASTM C936/C936M.In at least one embodiment, the compressive strength is determined afterfurther curing the glow-in-the-dark concrete block for 5-30 days, 10-29days, or 28 days.

As used herein, skid resistance refers to the friction force between arubber tire and a road surface. An inadequate skid resistance may leadto a higher risk of skid related accidents. In one or more embodiments,the surface layer of the glow-in-the-dark concrete block has a skidresistance value of 100-150, preferably 105-140, preferably 110-135,preferably 115-130, preferably 120-125. In one embodiment, the skidresistance reported herein is tested on a wet surface layer of theglow-in-the-dark concrete block. In another embodiment, the skidresistance reported herein is tested on a sandy surface layer of theglow-in-the-dark concrete block. The standard skid resistance valuerequired for difficult road conditions including sandy and/or wet roadsurface is about 65.

The glow-in-the-dark concrete blocks of the present disclosure may beused in a variety of areas ranging from pedestrian crossing, bicyclelanes, concrete barriers, curbstones, bollards for aesthetic effectand/or safety considerations. The glow-in-the-dark concrete blocks maybe advantageously used to display information by proper assembling theblocks in certain desirable shapes (e.g. a line, an arrow, a text, alogo) in circumstances of varying light. As a result of their chemicalstability and low degree of leaching (see Examples 8 and 9), theglow-in-the-dark concrete blocks cause no deleterious effect on users orthe environment.

A further aspect of the present disclosure relates to a luminescentconcrete material including a cured form of the luminescent concreteslurry disclosed herein in any of its embodiments. The curing for theluminescent concrete material may be similar to the aforementionedprocedures and conditions. The luminescent concrete material may be usedin concrete restoration, pavement decoration, wall plaster, swimmingpool plaster, tile setting materials such as mortars and grouts.

The examples below are intended to further illustrate methods andprotocols for preparing, characterizing and assessing the luminescentconcrete composition of the present disclosure, and are not intended tolimit the scope of the claims.

Example 1 Overview

The current disclosure involves the use of strontium aluminate, a GiDpowder (FIGS. 2A and 2B) in concrete for the development and testing ofnew interlock blocks that can be applied on infrastructure projects.Furthermore, environmental testing of the newly developed GiD amendedconcrete was conducted to estimate impacts on the human health andsurrounding environment. The objectives of the present disclosureinclude:

-   (i) describing suitable proportions of GiD material and other    concrete ingredients to achieve desirable glow intensity, duration    and strength;-   (ii) conducting mechanical testing of the developed specimen to    assess real-world feasibility of the GiD concrete; and-   (iii) performing environmental testing of the developed specimen to    analyze real-world environmental impact of the GiD concrete.

Example 2 Materials

A total of 54 concrete interlock blocks were casted using ordinaryPortland grey cement with specific gravity of 3.15. Each interlock blockcomprises two portions: the top surface layer and the bottom base layer.The bottom layer of the block contained a cement, fine and courseaggregates, as the bottom layer was the main load bearing portion. Thetop layer was smooth finished and mainly contained cement and a fineaggregate, as shown in FIGS. 3A, 3B and 3C. The dimension of theinterlock block was 200 × 100 × 80 mm.

The chemical composition of the ordinary Portland cement (OPC) by weight(%) was as follows: CaO = 64.3, SiO₂ = 22, Al₂O₃ = 5.64, Fe₂O₃ = 3.8,K₂O = 0.36, MgO = 2.11, Na₂O = 0.19 and equivalent alkalis (Na₂O +0.665K₂O) = 0.42, loss on ignition was 0.7, C₃S = 55, C₂S = 19, C₃A = 10and C₄AF = 7.

Desert sand possessing a bulk specific gravity of 2.66 and waterabsorption of 0.60%, respectively, was used as the fine aggregate. Thewater-to-cement ratio was 0.41 and the weight concentration of the fineaggregate is 55% relative to the dry composition.

The base layer included limestone as the course aggregate. The limestonehad a maximum size of 10 mm was and was graded in accordance with ASTMC33. In addition, ASTM C33 conditions for coarse aggregate grading weresatisfied by selecting aggregate size of 10 and 4.75 mm partitioned 20%and 80% by mass respectively. The limestone had a bulk specific gravityof 2.41 and water absorption of 2.03%, respectively.

A typical mixing process began by weighing the cement, sand, and GiDpowder using a weighing scale with accuracy of the nearest thousandth.Firstly, the GiD powder and sand were hand mixed using a mixer and thenthe cement was added along with water content. GiD powder was used inthree different proportions, i.e. 10%, 15% and 20% replacement of sandto investigate the effect of the addition of GiD powder on the strength,intensity of glow, and glow duration of the interlock block.

The entire mix was then place in the hydraulic press and only the top 5mm layer of the interlock block was cast-in-place as shown in FIG. 3A.The rationale behind using GiD concrete material only as the top layerof the interlock block was that the bottom part of the tile would beembedded underneath the ground surface, and the light would not be ableto reach the GiD material. As a result, any addition of GiD into thebottom layer would result in a cost increase without any added benefit.Andrew et al. [Andrew, A., Taylor, W., Tao, B. and Weiss, J. (2015):“Assessing the Performance of Glow in the Dark Concrete”, TransportationResearch Record: Journal of the Transportation Research Board, 41, pp.1-14. DOI: 10.3141/2508-04, incorporated herein by reference in itsentirety] developed a GiD liquid sealant via mixing GiD powder with soymethyl ester polystyrene. From the experimentation the researchers foundthat a GiD layer with a thickness beyond 3 mm had a negligible effect onthe glow intensity and duration. However, the GiD sealant produced bythe past researchers had little to no durability thus could not beapplied in a harsh, real-world environment. Furthermore, the researchersdid not shed any light on the impact of using GiD material on theenvironment. FIGS. 4A and 4B depict the glow-in-the-dark (GiD) interlockblock samples in the day light and night light setting, respectively.The samples showed the ability to absorb energy during the day time andrelease the stored energy as visible light during the night time. Inorder to reduce cost of production, only the top 5 mm layer of theinterlock tiles was replaced with the GiD amended concrete.

Durability and environmental impact assessments were conducted on theGiD interlock block samples in order to ascertain their readiness forreal-world application. The objective of the testing was to providescientific data related to the mechanical properties of the newlydeveloped GiD interlock blocks and also to determine the effects of GiDmaterial on human health and the environment. Furthermore, a detailedcost analysis of the samples was conducted and compared to the cost ofexisting regular concrete block samples. This helped determination ofsuitability of the GiD interlock blocks in-terms of real worldapplication. The proceeding sections detail the results of theseassessments.

Example 3 Compressive Strength Testing

ASTM C936/C936M was adopted for all the testing conducted on concretepaving units. 54 block samples were casted with a 200 × 100 × 80 mmdimension and a thickness/width aspect ratio of 0.8. All the sampleswere air dried for 24 hours in a humidity controlled room at 90%humidity level. The samples were then placed in a temperature controlledcuring tank at a temperature between 22 - 24° C. for 28 days. Threeregular block samples without any material modification were testedunder compressive loading as control samples. The control samples had anaverage strength of 49.47 MPa. Nine GiD modified samples, includingthree each with 10%, 15%, and 20% replacement of sand with the GiDpowder were tested under compressive loading. As shown in Table 1, theseGiD modified samples had an average compressive strength of 45.48 MPa.

From the results, it is evident that an increase in the content of GiDpowder had a negligible effect on the compressive strength since thedifference between samples having different GiD contents was below 5%.However, the GiD amended samples reported a 8.1% lower strength onaverage as compared to regular samples. This loss in compressivestrength could be attributed to the reduced compressive force applied onthe GiD samples during the manufacturing process. Since only the toplayer of the interlock block was replaced, the production line wasstopped after the base layer was cast during regular manufacturingprocess, the GiD top layer was then manually placed in the block molds,and lastly the hydraulic pressure was applied. Such interruption andresumption of the hydraulic press resulted in reduced pressureapplication on the new GiD samples, hence led to the reduced compressivestrength. Additionally, it should be noted that the samples will beembedded in the ground and surrounded by other interlock blocks inreal-world conditions, thus the load carrying capacity would increaseowing to confinement provided by adjacent blocks. FIGS. 5A, 5B and 5Cpresent typical cracking patterns of the tested samples. From theexperimentation, it was observed that the samples tended to fail owingto cracks on the edges.

In addition, compression strength testing was performed on samples afterthey were subjected to thermal loading. The rationale behind conductingcompressive strength testing after the application of thermal cyclingwas to simulate real-world behavior after application of the GiD blockson pavements. Six samples, two of each proportioning, were tested afterbeing subjected to thermal cyclic loading. The average compressivestrength was 43.79 MPa, which was approximately 4% lower than regularGiD samples. This slight loss in strength can be attributed to theevaporation of water molecules from the pores of the GiD interlock blocksamples, which resulted in a pours sample hence led to a loss incompressive strength. Importantly, no difference in the strength wasobserved by varying the percentage of GiD powder in the concrete. Thiscould be reasoned by the fact that only the top 5 mm layer was emendedwith GiD powder, and the top layer was not the load bearing portion ofthe interlock block, thus the effect GiD powder on overall strength ofthe block was negligible. The details of the thermal testing areprovided in the proceeding section.

TABLE 1 Compressive strength testing of control and GiD blocks Sr. No.Area (mm²) Load (N) Comp. Str. (MPa) CONTROL 1 20000 985200 49.26 220000 997400 49.87 3 20000 985400 49.27 Average 49.47 GiD SAMPLES 120000 945170 47.2585 2 20000 907240 45.362 3 20000 917440 45.872 4 20000865300 43.265 5 20000 906700 45.335 6 20000 917000 45.85 7 20000 90480045.24 8 20000 918700 45.935 9 20000 905100 45.255 Average 45.48

Example 4 Thermal Testing

Thermal cyclic testing of the developed GiD concrete samples wasconducted to evaluate the suitability of application of these samples inreal-world conditions. Since in real-world the samples will be exposedto harsh environmental conditions where cyclic thermal loadings mayoccur, the objective of this testing was to analyze the effect ofthermal loading on GiD material. Fundamentally, the testing was to checkif melting or expansion of GiD emended material would occur when exposedto increased temperature. In this regard, two types of thermal loadingtest were designed. The first test was designed to simulate the dailycyclic thermal loading induced owing to sunlight. For this purpose threesamples were left to cool off for 24 hours in a temperature controlledlaboratory at 26° C., afterwards the samples were placed in an oven andthe temperature was increased to 60° C. with a 5° C. increase rate perminute. The samples were kept at 60° C. for 30 mins and then cooled backto room temperature. 15 cycles of this thermal loading were applied oneach sample. From the experimentation, it was observed that samples didnot demonstrate any thermal stress, material melting, delamination, ordeformation. For the second type of thermal loading, three samples wereleft to cool off at 26° C. for 24 hours, later these samples were placedin the oven and temperature was increased to 160° C. at a 5° C. increaserate per minute. The samples were held at 160° C. for 15 mins. This testwas designed to simulate the extreme condition when placement of hotbitumen on the road surface occurs adjacent to GiD interlock blocks.From the experimentation, no damage to the samples was observed. Thisshowed that the prepared GiD samples could be applied in real-worldsituations.

Example 5 Skid Resistance Testing

Since the application of the GiD samples presented in the currentdisclosure is for bicycle ways, pedestrian crossings, walk ways, etc.,it was necessary to evaluate the skid resistance of the developedsamples under varying weather conditions. For this purpose, skidresistance test was performed under air dry conditions, saturatedsurface conditions, as well as sandy conditions. The skid resistancetest represented the frictional resistance property of the prototype.The standard requirement of skid resistance value (SRV) for mostdifficult sites is 65. Table 2 presents the SRV for dry, wet and sandyconditions. From the results, it is evident that the developed prototypeis suitable for any weather condition.

TABLE 2 Skid resistance value Sr. No. Sample Size (mm) Surface ConditionSkid Average 1 200 × 100 × 80 Wet 135 2 200 × 100 × 80 Dry 120 3 200 ×100 × 80 Sandy 105

Example 6 Particle Size Analysis

As shown in FIG. 6 , particle size analysis was conducted on the GiDpowder. The GiD powder size distribution showed a D₅₀ at 4.05 µm and aD₉₀ at 5.5 µm. Such particle size distribution was suitable for theutilization of the powder on the top layer of the interlock blocks.Furthermore, this particle size distribution has an added advantage thatthe mortar prepared using this GiD luminance powder can be applied toconcrete barriers and curbstones for added visibility and safety. Inaddition, GiD based disks that can be used as lane separators on roadsurfaces may be prepared by dissolving GiD powder in bio-degradablenon-toxic solvent and casting the samples. However, this is subjected tofuture research and development.

Example 7 Luminance Testing

Streetlights consume approximately 2.3% of the global electricity energy[Kostic, M., and L. Djokic, L. (2009): “Recommendations for energyefficient and visually acceptable street lighting”. Energy, 34 (10), pp.1565-1572, incorporated herein by reference in its entirety]. GiDmaterials may provide an energy efficient alternative to the increasingdemand of electricity. The developed prototype may be applied on bicycleways, walkways, along with other applications to improve road safety andesthetic appeal, while at the same time lower the energy consumption.Using GiD material in the form of emulsion or sealant has drawbacks suchas lack of durability [Andrew, A., Taylor, W., Tao, B. and Weiss, J.(2015).: “Assessing the Performance of Glow in the Dark Concrete”,Transportation Research Record: Journal of the Transportation ResearchBoard, 41, pp. 1-14. DOI: 10.3141/2508-04, incorporated herein byreference in its entirety]. Depending on the traffic conditions, it wasestimated that road traffic can erode paint coating applied on roadwithin a period of 0.7-2.5 years. It is evident that embedding the GiDmaterial into the concrete surface is a suitable application. In thisregard luminance testing was conducted on the developed prototype tojudge the feasibility.

A light measuring photometer was used to analyze the intensity andduration of light emitted in candelas per square meter (cd/m²). Beforethe commencement of luminance test, the base reading of the GiDinterlock block sample was established by placing the sample in a darkbox for 24 hours to eradicate any excitation from external light source.The base reading was recorded at a level where the human eye could notdiscern any light coming from the prototype, i.e. 0.0003 cd/m²[Matsuzawa, T., Aoki, Y., Takeuchi, N. and Murayama, Y. (1996).: “A NewLong Phosphorescent phosphor with high brightness”, 143(5), pp. 4-7,incorporated herein by reference in its entirety]. Before measuring theglow of the samples, the samples were charged/excited using a 150 wattxenon lamp. Such choice was made because the light emitted by a xenonlamp closely matched sun light in terms of spectral wavelength. Thedistance between the light source and GiD prototype was adjusted so thatthe entire surface of the sample was covered.

Three different samples i.e. 10%, 15%, and 20% addition of GiD sampleswere tested under three individual excitation conditions i.e. 5, 10, and15 mins of excitation. The procedure of glow measurement experimentincludes excitation of the sample for the desired time duration, thenplacing the photometer on top of the sample 30 seconds after the lampwas switched off, and starting the data recording. The data recordingwas conducted for a minimum of 9 hours (540 min). The rationale behindchoosing this time length was to see if the GiD samples can glow for 9hours without the presence of any sunlight, since the samples have amain function to glow during night time. FIG. 7 presents the result of 9experimentation setups, 3 samples each of 10%, 15% and 20% addition ofGiD powder excited for 5, 10 and 15 minutes. From the presented resultsit is evident that as the percentage of GiD material increases theintensity of glow increases, while the duration of excitation had littleeffect on the duration of glow. This can lead to the conclusion thatonce the GiD material is fully charged it can keep glowing for thedesired amount of time. However, the intensity of glow depends upon thepercentage addition of GiD material. Furthermore, from the analysis onthe results presented in FIG. 7 , it was observed that there was 20%increase in glow intensity by increasing the GiD content from 10% to15%, however, only 8% increase in glow intensity was recorded forincreasing the GiD content from 15% to 20%. Hence, it can be seen thatthe percentage gain in glow intensity reduced with increasing GiDcontent, whereas the cost of manufacturing would increase exponentiallyby increasing the GiD content. Hence, it can be concluded that 20% is adesired percentage of GiD material for achieving sufficient glow andreasonable cost. The cost analysis and environmental impact assessmentof the developed prototype is presented in the proceeding section.

Example 8 Environmental Risk Assessment

Over the last few years, there is a significant rise in the assessmentof environmental compatibility of construction materials [Victoria, E.(1995).: “Environmental Guidelines for Major Construction Sites”,incorporated herein by reference in its entirety]. Concrete structuresconstructed using these materials experience long term exposure withsoil, ground water, and drinking water. The approval of utilization ofcertain materials in buildings or concrete structures is not only basedon technical or economic aspects but is also greatly influenced by itsenvironmental impact [Collivignarelli, C., Sorlini. S. (2002): “Reuse ofmunicipal solid wastes incineration fly ashes in concrete mixtures”,Waste Management, 22, 909-912, incorporated herein by reference in itsentirety]. FIG. 8 depicts the material feasibility triangle. For amaterial to be viable for use in the construction industry, itstechnical, economic and environmental impacts need to be evaluated.Concrete structure may contain small quantities of trace elements viaraw materials. The concentration of trace elements in concrete structureis an important aspect for the environmental risk assessment. Forexample, by regulation the trace element concentration in German cementshould be within a similar order as in natural rock, soil and clayregardless of whether additives are used. Numerous investigationsconfirmed that most trace elements such as cadmium, chromium, arsenic,antimony etc., were found in insoluble forms in mortars and concretesand were released into the soil in tiny quantities. This indicates thatthe construction material must comply with obligatory requirements whichinclude stability, fitness for use, durability, and essential protectionfor hygiene, health and the environment. Therefore, in order to evaluatethe environment compatibility of GiD powder and GiD amended concrete,chemical and elemental composition analyses were performed. The resultsof such testing are provided in the proceeding section.

(I) Risk Assessment Threshold of GiD Amended Concrete

The risk evaluation of a material can be determined by considering itspotential toxicity and exposure routes. These are the key tools toidentify risks posed by contaminants in material and evaluate theenvironmental feasibility and impact on human health of the material.The toxicity of the material may depend on the presence of traceelements. The material can be classified as acute or highly lethal basedon the concentration of toxic chemical. Toxicity criteria arecategorized in humans and ecosystems. For humans, it can be classifiedas cancerous and noncancerous impacts, and for environment it isassociated to pollution and community level impact. Toxicity analysisincludes chemical and elemental composition, and leaching analyses. Themain objective of analyzing the toxicity is to compare the concentrationof elements in GiD amended concrete with regulatory standards such assoil cleanup level at residential and commercial scale and Safe DrinkingWater Act (SDWA) for primary drinking water as stipulated by UnitedStates Environmental Protection Agency (US EPA). Table 3 and 4 show alist of concentration limit of elements in drinking water and soilcleanup levels, respectively. The quantification of toxicity andcomparison to regulation standard values provide information to aneffective control of the level of contaminant effecting human health andenvironment. The degree of toxicity depends on the level ofcontamination and its duration. It is not only related to the toxicityof the material, but also dependent on how the material is exposed orcomes into contact with organisms. Therefore, the degree of toxicity isassociated with the level of exposure. The possible exposure routes forthe present analysis were (i) ingestion which affects organs (liver,nervous, kidneys) and cancerous impact, (ii) inhalation associated withexposure due to contaminated air, and (iii) dermal exposure due to skincontact with contaminated soil.

TABLE 3 Maximum concentration limit (MCL) of national primary drinkingwater regulations Contaminant Name TC Limit (mg/L) SDWA MCL (mg/L)Arsenic 5.0 0.01 Barium 100.0 2 Cadmium 1.0 0.005 Chromium 5.0 0.1Mercury 0.2 0.002 Lead 5.0 0.015 Silver 5.0 0.10 SDWA: Safe DrinkingWater Act 1974, United States Environmental Protection Agency (USEPA)

TABLE 4 Soil cleanup target level of some contaminants Contaminant NameDirect exposure Residential (mg/kg) Commercial (mg/kg) Nitrate 5.0 -Sulfate 100.0 7600 Lead 1.0 1400 Cadmium 5.0 1700 Mercury 0.2 17Aluminum 5.0 - Arsenic 5.0 12

(II) Procedure of Toxicity Analysis

About 6 grams of GiD powder and concrete was mixed with 18 mL ofdeionized water in a 50 mL centrifuge tube. The solution was shaken forabout 15 minutes, followed by centrifugation for 30 minutes at 5500 rpm,and filtration. The filtrate was stored in a refrigerator for chemicaland elemental analyses. The mobile phase was prepared by taking 12 mMNaHCO₃ and 0.6 mM Na₂CO₃ prepared by weighing 0.0636 g of NaHCO₃ and1.008 g of Na₂CO₃ in one liter of deionized water. Shimadzu HighPerformance Liquid Ion Chromatography (UFLC) equipment was used tomeasure anions such as (chloride, nitrate, sulfate, and phosphate). Fourdifferent standard levels were prepared by dividing the molar mass ofNaCl (58.5 g/mol) by the molar mass of Cl (35.5) to yield a mass of 1.65g of Cl⁻. The second standard was prepared by dividing the molar mass ofNaNO₃ (84 g/mol) by the molar mass of NO₃ which was 62 g/mol to yield amass of 1.37 g. The third standard was prepared by dividing the molarmass of KH₂PO₄ (136.09 g/mol) by the molar mass of PO₄ (94.97 g/mol) toyield a mass of 0.14326 g of PO₄ ⁻³. The last standard was prepared bydividing the molar mass of Na₂SO₄ (142 g/mol) by the molar mass of SO₄ ⁻(96 g/mol) to give up a mass of 1.48 g. The masses were dissolved in oneliter of deionized water to make 1000 ppm solution, and then diluted to1.56 ppm, 3.125 ppm, 6.25 ppm, 12.5 ppm, 25 ppm, 50 ppm, 75 ppm, and 100ppm respectively for accurate calibration. In addition, inductivelycoupled plasma optical emission spectrometry (ICP-OES) was used as ananalytical approach to evaluate the presence of various chemicalelements. ICP-OES analysis of GiD powder and GiD amended concrete wasused to evaluate its chemical composition and to determine the level ofvarious chemical elements. The results of this analysis are provided inthe proceeding section.

(III) Determination of Concentration of Anions in GiD Powder and GiDAmended Concrete and Its Comparison With Soil Cleanup Target Levels

Presence of anions such as chloride, phosphate, and sulfate in concreteat high concentration level can lead to corrosion of steelreinforcement. This causes the degradation of reinforced concretestrength and significantly affects the structural integrity. For thisreason, the allowed concentration levels of these anions in a reinforcedconcrete structure are strictly controlled as they have a considerableimpact on structural durability. Moreover, in regards to environmentalcompatibility, these anions are highly toxic and serious threat tomarine life and human health when present above their acceptableconcentration limit. Their existence in water often produces undesirabletaste and ingestion of these anions can cause major health effect, e.g.sulfate is laxative action [Boyd, C. E., Massaut, 1 (1999).: “Risksassociated with the use of chemicals in pond aquaculture”, Aqua-culturalEngineering, 20, 113-132, incorporated herein by reference in itsentirety], excess phosphate inhalation significantly affects bothcardiovascular and musculoskeletal systems [Naus, D., Mattus, C., andDole, L. (2007).: “Final Report, Assessment of Potential PhosphateIon-cementitious Materials Interactions”, US Nuclear RegulatoryCommission, Office of Nuclear Regulatory Research, incorporated hereinby reference in its entirety]. The concentration of these ions presentin GiD powder and GiD amended concrete are listed in Table 5. Theresults shown in table 5 clearly confirm that the content of all fouranions in both GiD powder and GiD amended concrete were below 100 mg/kgas required by US EPA. The concentration ranges in GiD powder and GiDamended concrete were found in the order of: nitrate > chloride >sulfate > phosphate. The level of anions content in GiD powder and GiDamended concrete is within acceptable range when compared to soilcleanup target levels for residential and commercial applications [Code,F.A. (2005).: “Development of soil cleanup target levels (SCTLs)”,incorporated herein by reference in its entirety]. Therefore, based onanions results, it appears that the application of GiD amended concretein both residential and commercial structures is environmentally viableand poses no threat to human health.

TABLE 5 Comparison of concentration of anions in GiD powder, GiD amendedconcrete with SCTL Sample Chloride (mg/Kg) Nitrate (mg/Kg) Phosphate(mg/Kg) Sulfate (mg/Kg) GiD Powder 40.41 84.51 <1 7.83 GiD Concrete18.09 5.87 <1 8.78 SCTL (residential) 2005 (DE) 3100 140000 19 450 SCTL(commercial) 2005 (DE) 37000 ∗ 57 7600 SCTL = Soil Cleanup Target Level

Example 9 Determination of Elemental Composition of GiD Powder and GiDAmended Concrete and Its Comparison With WCTL

Contamination of heavy metals in water, soil, and air is an alarming andsevere issue worldwide. These heavy metals produce harmful impact onboth ecosystem and human health. Therefore, it is important to elucidatethe behavior of heavy metal in concrete to prevent such hazardouseffects. Table 6 shows that lithium, lead, aluminum, cadmium, cobalt andcopper are the main heavy metals in GiD powder with concentrations of437.591, 379.111, 285319, 185.523, 258.118, and 1056.672 mg/kg,respectively. The concentrations of other elements including As, Cr, Fe,and Zn were found below the detection limit. Similarly, in case of GiDamended concrete, the content of trace elements appeared in the orderof: Ca > Al > Na > Mg > Fe > Li > Cu > Pb. Comparing GiD trace elementscontent with soil cleanup target level, the concentrations of Al, Cd andCu were observed higher than acceptable limit of residential directexposure. However other elements were below the acceptable range.Furthermore, for GiD amended concrete, the concentration of all theelements was found to be below the acceptable range. The order ofconcentration of elements in GiD amended concrete was found as Ca > Al >Mg > Na > Fe > Cu > Pb. In addition, as shown in FIG. 9 and FIG. 10 ,the major content of contaminant present in concrete were aluminum,iron, copper, and lead. Therefore, the trace element analysis clearlyconfirmed that the concrete structure contained toxic contaminantconcentration below the standard protective regulations regarding bothhuman and environment.

TABLE 6 Comparison of concentration of anions in GiD powder, GiD amendedconcrete with WCTL Smp Fe K Li Mg Na Ni Pb mg/kg 1) <1 139.142 437.591240.642 10.083 184.850 379.111 2) 3584.124 <1 130.291 4450.972 4540.593<1 42.175 3) 53000 ^(∗) 1700 ^(∗) ^(∗) 340^(∗∗) 400 4) ^(∗) ^(∗) 44000^(∗) ^(∗) 35000 1400 Smp Al As Ca Cd Co Cr Cu mg/kg 1) 285319.52 <11726.838 185.523 258.118 <1 1056.672 2) 22764.724 <1 204184.36 <1 <1 <1128.031 3) 80000 2.1 ^(∗) 82 1700 210 150 4) ^(∗) 12 ^(∗) 1700 42000 47089000 1) GiD Powder 2) GiD Concrete 3) WCTL (residential) 2005 (DE) 4)WCTL (commercial) 2005 (DE) ^(∗)Contaminant is not a health concern forthis exposure scenario ^(∗∗)Direct exposure value based on acutetoxicity considerations. This criterion is applicable in scenarios wherechildren might be exposed to soils (e.g. residences, schools,playgrounds)

Example 10 Cost Analysis Environmental Risk Assessment

The cost analysis of the developed prototype as shown in FIG. 4 wasconducted to evaluate the increase in cost that occurred due to theaddition of GiD material. The cost analysis was conducted using 20% GiDaddition and taking into account of the real-world market prices ofregular non-glowing interlock blocks. The details of the cost analysisare provided below:

-   Total number of 200 × 100 × 80 mm interlock blocks in 1 m² area = 50-   Cost of 1 m² regular non-glow interlock blocks = SR 25 (US$ 6.7)-   Cost of one, 200 × 100 × 80 mm interlock block = SR 0.5 (US$ 0.133)-   Cost of 20% GiD for one 200 × 100 × 80 mm interlock block = SR 3.05    (US$ 0.81)-   Total cost of new one GiD interlock block = SR 3.55 (US$ 0.94)-   50% replacement of GiD blocks in 1 m² area = 25 × 3.55 = SR 88.75    (US$ 23.64)-   50% cost of regular interlock blocks = 25 × 0.5 = SR 12.5 (US$ 3.33)-   Total Cost of 1 m² area at 50% GiD samples = SR 101.25 (26.97)-   Percentage increase in cost = 102.5%

It should be noted that the above mentioned cost are related to samplesprepared for laboratory testing and development. Furthermore, once themanufacturing is conducted on a larger scale, the cost of production,material and procurement can be reduced. The objective of presenting thecost analysis is to provide insight into additional cost together withincrease in safety, sense of security, energy efficiency, and livingcondition as a result of the real-world application of the presentedinnovation.

Example 11

The development, testing, and environmental impact assessment ofglow-in-the-dark amended concrete is presented. GiD interlock blockshave been developed which can be applied to various infrastructurelocations. From the results and discussion of the present disclosure,the following conclusions can be drawn:

-   (i) GiD amended interlock block samples experienced 8.1% strength    drop compared to regular interlock blocks. This loss in strength    could be attributed to reduced compressive force applied during    manufacturing;-   (ii) GiD amended interlock block samples showed good resilience    against thermal cycling and performed exceptionally in skid    resistance test;-   (iii) luminance testing revealed that glow intensity increased with    increasing GiD content, however, the duration of glow was not    affected with the duration of excitation beyond 5 mins.-   (iv) environmental impact assessment of GiD amended concrete    revealed that the material is safe for application in real world    concrete structures. Furthermore, the material can be categorized as    clean material from concrete leaching aspect, as all the detected    trace elements (Ca, Al, Mg, Na, Fe, Cu, Pb) were below the    acceptable limits set by US-EPA for soil and water clean-up.-   (v) cost analysis for 20% GiD content at 50% replacement for 1 m²    interlock blocks revealed approximately 100% cost increase. This    cost increase can be evaluated by comparing the advantages of the    GiD amended concrete including increase in safety, and reduction in    energy cost.

The findings presented herein can be used by regulatory authorities todevelop regulations that govern the application of this newly developedprototype on infrastructure projects. Additionally, the cost analysis ofusing GiD material on the interlocking blocks used for walkways wasperformed to show the cost increase that would occur relative to theapplication of the newly developed material in real-world.

The presented work was conducted using grey cement. Cement with varyingcolor pigments such as white, yellow, red and orange etc. can also beused.

1-20. (canceled)
 21. A luminescent concrete composition, comprising: acement; a fine aggregate comprising sand; and phosphorescent aluminateparticles, wherein a weight ratio of the aluminate particles to the fineaggregate is in the range of 1:2 to 1:20; and wherein the luminescentconcrete composition has an intensity of glow of 2-15 candelas persquare meter for a period of 0.1-10 hours upon excitation with sun lightfor 2-20 minutes.
 22. The luminescent concrete composition of claim 21,wherein the phosphorescent aluminate particles comprise a rare earthelement doped strontium aluminate.
 23. The luminescent concretecomposition of claim 22, wherein the rare earth element is at least oneselected from the group consisting of cerium, dysprosium, europium, andneodymium.
 24. The luminescent concrete composition of claim 23, whereinthe rare earth element doped strontium aluminate further comprises apromoter selected from the group consisting of boron, lithium, sodium,potassium, magnesium, calcium, barium, chromium, and manganese.
 25. Theluminescent concrete composition of claim 21, wherein the phosphorescentstrontium aluminate particles have an average particle size of 1-15 µm.26. The luminescent concrete composition of claim 21, wherein the sandhas a bulk specific gravity of 2.2-2.8, and a water absorption of0.2%-1.0%.
 27. The luminescent concrete composition of claim 21, whichhas a weight percentage of the fine aggregate ranging from 35-60 wt%relative to a total weight of the luminescent concrete composition. 28.The luminescent concrete composition of claim 21, wherein the cement isan ordinary Portland cement.
 29. The luminescent concrete composition ofclaim 21, which has a weight percentage of the cement ranging from 30-60wt% relative to a total weight of the luminescent concrete composition.30. The luminescent concrete composition of claim 21, consistingessentially of the cement; the fine aggregate comprising sand; andphosphorescent strontium aluminate particles, wherein a weight ratio ofthe phosphorescent strontium aluminate particles to the fine aggregateis in the range of 1:2 to 1:20.
 31. A glow-in-the-dark concrete block,comprising: a surface layer comprising a cured luminescent concrete; anda base concrete block, wherein the cured luminescent concrete comprises:a cement; a fine aggregate comprising sand; and phosphorescent aluminateparticles, wherein a weight ratio of the phosphorescent aluminateparticles to the fine aggregate is in the range of 1:2 to 1:20; andwherein the cured luminescent concrete has an intensity of glow of 2-15candelas per square meter for a period of 0.1-10 hours upon excitationwith sun light for 2-20 minutes; and wherein at least a portion of asurface of the base concrete block is coated by the surface layer. 32.The glow-in-the-dark concrete block of claim 31, wherein the surfacelayer has a thickness of 1-20 mm, and wherein a thickness ratio of thesurface layer to the base concrete block is in the range of 0.02:1 to0.2:1.
 33. The glow-in-the-dark concrete block of claim 31, wherein thebase concrete block comprises a cured form of a concrete slurrycomprising cement, a fine aggregate comprising sand, a coarse aggregatecomprising limestone, and water, and which is devoid of phosphorescentaluminate particles.
 34. The glow-in-the-dark concrete block of claim33, wherein the limestone has an average particle size of 2-15 mm, abulk specific gravity of 2.0-3.0, and a water absorption of 1.0%-3.0%.35. The glow-in-the-dark concrete block of claim 31, which has acompressive strength of 43-50 MPa according to ASTM C936/C936M.
 36. Theglow-in-the-dark concrete block of claim 31, wherein the surface layerhas a skid resistance value of 100-150.
 37. The glow-in-the-darkconcrete block of claim 31, wherein a volume of the base concrete blockis greater than that of the surface layer.